This invention relates to the field of electronic test equipment, and more particularly to a programmable tester capable of automatically testing a variety of electronic units.
With the introduction into the marketplace of sophisticated electronic equipment consisting of analog, digital and hybrid circuitry, there has developed a market for a portable tester capable of automatically testing this equipment. This need for a portable tester is further enhanced when one recognizes that much of the electronic equipment to be tested is itself portable, i.e., it is quite frequently moved and situated at different locations or is part of an operating environment which is portable, such as an aircraft.
A number of systems to measure the response of a unit under test (UUT) to preselected applied stimuli are known in the art. A primary purpose of the known systems has been to determine whether the unit under test is operating, or is operable, in accordance with predefined performance specifications. One of the significant disadvantages of the known systems of this type is that, to a large extent, they have been hard wired and specially configured to test only one or at most a few similar functional UUT's. Accordingly, it has been necessary to maintain a relatively large inventory of such expensive systems where large numbers of unrelated UUT's are to be tested.
One approach which attempts to solve the problems inherent in some of the known systems is described in U.S. Pat. No. 3,764,995. However, the disclosed system has several limitations and drawbacks associated therewith. In particular, its cost and size preclude cost-effective application in many areas of interest. Moreover, it also requires a large, very complex and costly interface device to adapt the unit under test to the tester.
A desirable automatic tester would have several important attributes. In particular, it should be capable of simple, low cost, rapid GO/NO-GO indentification of analog-hybrid-digital modules, present a simple interface to the unit under test, be programmable in a high level language, such as ATLAS, and provide for on-line modificaton of test parameters.
A tester having these attributes is disclosed in U.S. Ser. No. 748,853, assigned to the present assignee. The prior tester essentially incorporated a microcomputer-based test station, a set of test instruments, and test program interface. More particularly, a memory was provided for storing a test program that tested the operation of a unit undergoing test. A microcomputer executed the stored test program. Programmable stimulus generators were connected to the unit undergoing testing and a programmable response measurement apparatus was similarly connected to the unit undergoing testing. A programmable switching means selectively connected the stimulus generating means and the response measuring means. A display was provided for allowing visualization of the testing results.